The Healthy Eating Index (HEI) is a measure of diet quality in terms of conformance to the Dietary Guidelines for Americans. The Guidelines are the basis of nutrition policy for the US government, and are issued every 5 years by the USDA and US DHHS; the 2015 version was released in January 2016. The HEI is now being updated by colleagues at NCI and USDA to reflect the new guidelines and will be released as the HEI-2015. Based on the Scientific Report submitted by the Dietary Guidelines committee, it is anticipated that the HEI-2015 will retain many features of the current HEI-2010, but with modifications reflecting the addition of defined limits for added sugars and saturated fats. Diet quality indices such as the HEI are increasingly applied to prospective cohort data because of, 1) the relative ease and appeal of representing the complexity of the total diet with a standardized metric, and 2) their ability to readily translate findings into relevant public health messages (i.e., following a diet that aligns with dietary guidance is or is not associated with a specific health outcome). Given the recent release of the 2015 Dietary Guidelines for Americans and the associated HEI-2015 to be developed, there is a pressing need to establish the predictive criterion validity of the new HEI-2015 in a diverse cohort such as the Multi-ethnic Cohort, using all-cause, cancer, and cardiovascular disease mortality outcomes.